Robotic leg parallel to a ball screw

ABSTRACT

Disclosed are robotic systems, methods, bipedal robot devices, and computer-readable mediums. For example, a robotic system may include a robotic body, a robotic hip connected to the robotic body, and a ball screw connected to the robotic hip. Further, the robotic system may include a robotic leg connected to the robotic hip parallel to the ball screw. Yet further, the robotic hip includes a motor that is linearly movable to one or more positions along the ball screw between one end of the robotic leg and an opposite end of the robotic leg.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/045,074, filed Sep. 3, 2014.

BACKGROUND

One type of a robot system may be a humanoid robot. These roboticsystems may have a structure that resembles a human body. One examplerobot system may have a robotic head, two robotic arms, a main roboticbody, and two robotic legs. The two robotic legs may be used for bipedalwalking that mimics human walking. For example, each of the robotic legsmay include a robotic knee, a robotic ankle, and a robotic foot. Assuch, the robotic system may take steps to engage in bipedal walking.For instance, the robotic system may use one leg to bear weight of therobotic system while the other leg swings forward to take step in agiven direction.

SUMMARY

It may be challenging for a robotic system to engage in bipedal walking.For example, similar to human walking, the robotic system may besusceptible to tripping over an object in the way of its robotic legswinging forward to take a step. Further, the robotic system may haveinstabilities in its robotic knees, robotic ankles, and robotic feet.Yet, by connecting the robotic hip to the robotic leg such that therobotic hip is linearly movable along the robotic leg, some of theseinstabilities may be addressed. For example, the robotic leg may beconnected to the robotic hip such that it is fully rotatable around anaxis of rotation defined by the robotic hip. As such, each robotic legmay rotate around respective robotic hip joints to move the robotic legsin a “windmill” type fashion, thereby reducing the movements involvingrobotic legs swinging forward. Thus, the chances of the robotic systemtripping over objects may be decreased.

Further, in addition to the instabilities associated with the roboticknees, the robotic system may encounter stresses in certain parts of therobotic body, such as the robotic knees, the robotic ankles, and therobotic feet. These parts of the robotic system may encounter stressesand tensions that may eventually lead to the robotic system breakingdown. Thus, these robotic systems may eventually lead to worn parts,possibly requiring repairs and/or replacements. By connecting therobotic hip to a ball screw positioned parallel in the robotic leg, theweight of the robotic system may rest on the ball screw as opposed toone or more joints in the robotic system. As such, the ball screw maymake the robotic system more robust, possibly reducing the number ofjoints that require repairs and/or replacements.

In one implementation, a robotic system is provided. The robotic systemincludes a robotic body, a robotic hip connected to the robotic body,and a robotic leg connected to the robotic hip. Further, a first roboticfoot is connected to one end of the robotic leg and a second roboticfoot is connected to an opposite end of the robotic leg, where therobotic leg is fully rotatable around an axis of rotation defined by therobotic hip, and where the robotic hip is linearly movable along therobotic leg to one or more positions between the one end of the roboticleg and the opposite end of the robotic leg.

Another implementation includes moving, by a robotic system, a robotichip linearly along a robotic leg to one or more positions between oneend of the robotic leg and an opposite end of the robotic leg, where therobotic leg comprises a first robotic foot connected to the one end ofthe robotic leg and a second robotic foot connected to the opposite endof the robotic leg. Further, the implementation includes rotating, bythe robotic system, the robotic leg around an axis of rotation definedby the robotic hip.

In yet another implementation, a bipedal robot device is provided. Thebipedal robot device includes a robotic body, a robotic hip connected tothe robotic body, and a robotic leg connected to the robotic hip.Further, a first robotic foot is connected to one end of the robotic legand a second robotic foot is connected to an opposite end of the roboticleg, where the robotic leg is fully rotatable around an axis of rotationdefined by the robotic hip, and where the robotic hip is linearlymovable along the robotic leg to one or more positions between the oneend of the robotic leg and the opposite end of the robotic leg.

In still another implementation, a robotic system is provided. Therobotic system may include a robotic body, a robotic hip connected tothe robotic body, and a robotic leg connected to the robotic hip.Further, the robotic system may include means for moving the robotic hiplinearly along the robotic leg to one or more positions between one endof the robotic leg and an opposite end of the robotic leg, where therobotic leg comprises a first robotic foot connected to the one end ofthe robotic leg and a second robotic foot connected to the opposite endof the robotic leg. Further, the robotic system may include means forrotating the robotic leg around an axis of rotation defined by therobotic hip.

In another implementation, a robotic system is provided. The roboticsystem includes a robotic body, a robotic hip connected to the roboticbody, a ball screw connected to the robotic hip, and a robotic legconnected to the robotic hip parallel to the ball screw, where therobotic hip comprises a motor that is linearly movable to one or morepositions along the ball screw between one end of the robotic leg and anopposite end of the robotic leg.

Yet another implementation includes moving, by a robotic system, a motorof a robotic hip linearly along a ball screw connected parallel to arobotic leg, where the motor moves to one or more positions along theball screw between one end of the robotic leg and an opposite end of therobotic leg, where the robotic hip is connected to a robotic body.Further, the implementation includes rotating, by the robotic system,the robotic leg around an axis of rotation defined by the robotic hip.Based on rotating the robotic leg, the implementation includes causingthe robotic leg to take a step.

In still another implementation, bipedal robot device is provided. Thebipedal robot device includes a robotic body, a robotic hip connected tothe robotic body, a ball screw connected to the robotic hip, and arobotic leg connected to the robotic hip parallel to the ball screw,where the robotic hip comprises a motor that is linearly movable to oneor more positions along the ball screw between one end of the roboticleg and an opposite end of the robotic leg.

In an additional implementation, a robotic system is provided. Therobotic system includes a robotic body, a robotic hip connected to therobotic body, a ball screw connected to the robotic hip, and a roboticleg connected to the robotic hip parallel to the ball screw. Further,the robotic system may include means for moving a motor of a robotic hiplinearly along the ball screw, where the motor moves to one or morepositions along the ball screw between one end of the robotic leg and anopposite end of the robotic leg, where the robotic hip is connected to arobotic body. Further, the robotic system may include means for rotatingthe robotic leg around an axis of rotation defined by the robotic hip.Based on rotating the robotic leg, the robotic system may include meansfor causing the robotic leg to take a step.

These as well as other implementations, aspects, advantages, andalternatives will become apparent to those of ordinary skill in the artby reading the following detailed description, with reference whereappropriate to the accompanying drawings. Further, this summary andother descriptions and figures provided herein are intended toillustrate implementations by way of example only and numerousvariations are possible. For instance, structural elements and processsteps can be rearranged, combined, distributed, eliminated, or otherwisechanged, while remaining within the scope of the implementations asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts aspects of a robotic system, according to an exampleimplementation.

FIG. 2 depicts aspects of a robotic system, according to an exampleimplementation.

FIG. 3 depicts aspects of a robotic system, according to an exampleimplementation.

FIG. 4 is a flow chart, according to example implementations.

FIGS. 5A and 5B depict aspects a robotic system, according to exampleimplementation.

FIGS. 6A and 6B depict aspects a robotic system, according to an exampleimplementation.

FIG. 7 is a flow chart, according to example implementations.

FIG. 8 depicts aspects of a robotic system, according to an exampleimplementation.

FIG. 9 depicts aspects of a robotic system, according to an exampleimplementation.

FIG. 10 depicts aspects of a liquid-cooled device, according to anexample implementation.

DETAILED DESCRIPTION

Example systems, methods, devices, and computer-readable mediums aredescribed herein. It should be understood that the words “example” and“exemplary” are used herein to mean “serving as an example, instance, orillustration.” Any implementation or feature described herein as beingan “example” or “exemplary” is not necessarily to be construed aspreferred or advantageous over other implementations or features. Otherimplementations can be utilized, and other changes can be made, withoutdeparting from the scope of the subject matter presented herein.

Thus, the example implementations described herein are not meant to belimiting. The aspects of the present disclosure, as generally describedherein, and illustrated in the figures, can be arranged, substituted,combined, separated, and designed in a wide variety of differentconfigurations, all of which are explicitly contemplated herein.

I. OVERVIEW

Among various challenges to bipedal walking, a robotic system may faceobstacles associated with the dynamics of its robotic legs. Inparticular, the robotic system may encounter instabilities withcontrolling a robotic hip connected to the robotic leg and furthermoving parts of the robotic leg such as a robotic knee, a robotic ankle,and a robotic foot. As such, a single step of the robotic system mayinvolve moving multiple parts of the robotic system. Thus, the roboticsystem may be susceptible to tripping due to such complex dynamics ofthe robotic system. Further, as noted, the robotic system may also comeacross objects in the path of a robotic leg swinging forward to take astep, increasing the chances of the robotic system tripping and falling.

Thus, example implementations herein describe robotic hips connected tothe robotic legs such that the robotic hips are linearly movable alongrespective robotic legs. Further, each robotic leg may be connected toits respective robotic hip such that each robotic leg is fully rotatablearound an axis of rotation defined by its respective robotic hip. Assuch, each robotic leg may rotate around its respective robotic hipjoint interchangeably to move the robotic legs in a “windmill” typefashion, propelling the robotic system forward. With less dynamicsinvolved with the robotic legs and reducing the motion of the roboticlegs swinging forward to take steps, the chances of the robotic systemtripping may be decreased.

In addition to the challenges noted above, robotic joints such asrobotic knees and robotic ankles may frequently encounter stresses andtensions during bipedal walking. For example, robotic knees mayencounter large torque forces that may eventually damage the roboticlegs. As such, additional implementations herein describe the robotichips connected to ball screws positioned parallel in the respectiverobotic legs. Thus, the weight of the robotic system may rest on theball screws as opposed to, for example, the robotic knees. The ballscrews may reduce the stress on the robotic joints and therefore, lessenthe number repairs and/or replacements.

II. EXAMPLE IMPLEMENTATIONS

FIG. 1 depicts aspects of a robotic system, according to an exampleimplementation. In some examples, robotic system 100 may includecomputer hardware, such as a storage 102, a communication component 104,a processor 106, actuators 108, and sensors 110. For example, one ormore of these hardware components may be designed for a robotic system100 such as a humanoid robot and/or a bipedal-robot device.

Storage 102 may be a memory that includes a non-transitorycomputer-readable medium having stored thereon program instructions. Theprocessor 106 may be coupled to the storage 102 to cause the roboticsystem 100 to perform operations based on executing these programinstructions. Further, the processor 106 may be coupled to thecommunication component 104 for communicating with other roboticsystems, robots, and/or devices. For example, communication component104 may be used to access one or more server devices of a network. Insome implementations, communication component 104 may include a wiredconnection including, for example, a parallel bus or a serial bus suchas a Universal Serial Bus (USB). Further, communication component 104may include a wireless connection including, for example, Bluetooth,IEEE 802.11, Cellular (such as GSM, CDMA, UMTS, EV-DO, WiMAX, or LTE),or Zigbee, among other possibilities.

Processor 106 may store, in the storage 102, data obtained from thesensors 110. In some examples, sensors 110 may include a gyroscope, anaccelerometer, a Doppler sensor, a sonar sensor, a radar device, alaser-displacement sensor, and/or a compass, possibly to measurelocations and/or movements of the robotic system 100. Yet further,sensors 110 may include an infrared sensor, an optical sensor, a lightsensor, a camera, a biosensor, a capacitive sensor, a touch sensor, atemperature sensor, a wireless sensor, a radio sensor, a sound sensor,and/or a smoke sensor, possibly to obtain data indicative of anenvironment of the robotic system 100. In addition, sensors 110 mayinclude a sensor that measure forces acting about the robotic system100. For example, sensors 110 may include a sensor that measures forces(e.g., inertial forces and/or G-forces) in multiple dimensions. Further,sensors 110 may include a sensor that measures torque (possibly referredto herein as a “force-torque sensor”), a sensor that measures groundforces (possibly referred to a “ground force sensor” and/or a “frictionsensor”), and a zero moment point (ZMP) sensor that identifies ZMPsand/or locations of the ZMPs, among other possibilities.

The robotic system 100 may also have actuators 108 that enable therobotic system 100 to initiate movements. For example, the actuators 108may include or be incorporated with robotic joints connecting roboticlimbs to a robotic body. For example, the actuators 108 may includerobotic hip joints connecting robotic legs to the robotic body. Further,the actuators 108 may include robotic knee joints connecting parts(e.g., robotic thighs and robotic calves) of the robotic legs. Yetfurther, the actuators 108 may include robotic ankle joints connectingthe robotic legs to robotic feet. In addition, the actuators 108 mayinclude motors for moving the robotic limbs. As such, the actuators 108may enable the mobility of the robotic system 100 in an environment ofthe robotic system 100.

The robotic system 100 may include one or more direct current (DC)motors, permanent magnet motors, fuel powered motors (e.g., gasolineand/or gas powered motors), and/or servo motors to move the roboticlimbs. Such motors may allow the robotic system 100 to have precisecontrol of its actuators 108 and the movement of the robotic limbs. Yet,such motors may also be heavy, thereby causing the robotic system 100 toconsume more power to move robotic limbs. Further, the weight of themotors may cause the robotic legs to make heavy impacts with the ground,possibly damaging the robotic legs over time and/or after traveling longdistances. In some implementations, the robotic system 100 may includehydraulic mechanisms to move the robotic limbs. The hydraulic systemsmay give the robotic system 100 more strength, enabling the roboticsystem 100 to lift heavy objects. Yet, the hydraulic mechanisms mayrequire pumps that may be bulky, taking up additional space in therobotic system. In addition, the hydraulic mechanisms may be difficultto control such that the robotic movements may appear spastic, jerky,and/or less precise.

Thus, the robotic system 100 may include smaller and/or lightweightmotors to move the robotic limbs. Yet, such motors may encounterchallenges as well. For example, the actuators 108 with smaller motorsmay deliver a limited amount of power. Thus, decreasing the size ofmotors may cause the robotic system 100 to be weaker. Further, drivingthe motors at higher speeds may cause the motors to emanate thermalenergy, possibly overheating the robotic system. Yet further, it may bedifficult to determine the internal temperature of the motors to preventthe robotic system from overheating.

FIG. 2 depicts aspects of a robotic system, according to an exampleimplementation. The robotic system 200 may include, for example, one ormore parts of the robotic system 100 in relation to FIG. 1. For example,the robotic legs 210 and 212 may include sensors 110, such as sensorsthat measure inertial forces and/or G-forces in multiple dimensions, aforce-torque sensor, a ground force sensor, a friction sensor, and/or aZMP sensor, among other possibilities.

As shown, a robotic body 202 that may include a battery 204, a radiator206, and a capacitor 208. The robotic system 200 may also include tworobotic hips 214 and 216, connecting the robotic body 202 to two roboticlegs 210 and 212, respectively. Further, the two robotic legs 210 and212 may include two robotic knees 218 and 220, two robotic ankles 222and 224, and two robotic feet 226 and 228, respectively. The roboticsystem 200 may weigh approximately 30 to 80 kilograms.

Battery 204 may be used to power the robotic system 200. Radiator 206may transfer thermal energy from one part of the robotic system 200 toanother for cooling the robotic system 200. The radiator 206 may provideliquids to cool the motors in the robotic system 200. Capacitor 208 maybe a multi-layered capacitor (e.g., a double-layered capacitor) operableto produce current in a shortened period of time. The capacitor 208 mayproduce currents to power the motors when the available power capacityin the capacitor 208 is lower than one or more capacity thresholds. Forexample, the capacitor 208 may supply varying amounts of current tomotors and drivers in the robotic legs 210 and 212, possibly morereliably than the battery 204. In some instances, the capacitor 208 mayoperate with an approximate voltage of 50-150 V, an approximatecapacitance of 7-21 farads, and an approximate internal resistance of25-150 mΩ.

The robotic system 200 may include one or more motors powered by thecapacitor 208. For example, the robotic system 200 may include one ormore of the motors that generate heat and are cooled by lowertemperature liquids around the motors. For example, the robotic knees218 and 220 may include motors cooled by liquids to achieve rotationalspeeds over approximately 1,000-2,000 degrees per second and overapproximately 350-700 newton meters (Nm) of torque.

Further, the motors cooled by liquids may be used to move robotic hips214 and 216. Additionally, these motors may be used to move the roboticlegs 210 and 212. In particular, these motors may be positioned in therobotic knees 218 and 220, and the robotic ankles 222 and 224. As such,the robotic system 200 may engage in bipedal walking, possiblyresembling the walking patterns of a human person. The weight of therobotic system 200 may shift on to each of the robotic legs 210 and 212interchangeably. In particular, the robotic system 200 may shift theweight on to the robotic foot 226 as the robotic leg 212 swings forwardto take a step. Further, the robotic system 200 may shift the weight onto the robotic foot 228 as the robotic leg 210 swings forward to take astep.

The robotic system 200 may be operable through remote controls. Yet, therobotic system 200 may also be operable autonomously. For example, therobotic system 200 may include control algorithms that maintain thestability and balance of the robotic system 200. These algorithms mayimplement a push-recovery capability such that the robotic system 200may maintain its balance after a force is applied to the robotic system200. This capability may cause the robotic system 100 to reposition therobotic legs 210 and 212, and the robotic feet 226 and 228. Forinstance, the robotic system 200 may maintain balance on the roboticlegs 210 and 212, and the robotic feet 226 and 228 after being hit,kicked, and/or shoved. The robotic system 200 may be capable ofcomputing approximately 70 to 270 placements of the robotic legs 210 and212, and the robotic feet 226 and 228 in less than approximately 0.1-1milliseconds.

FIG. 3 depicts aspects of a robotic system, according to an exampleimplementation. The robotic system 300 may take, for example, the formof a bipedal robot device and/or a multi-legged robot device such as aquadruped robot device, among various possibilities. Further, therobotic system 300 may include, for instance, one or more of the partsdescribed above in relation to robotic systems 100 and 200 shown inFIGS. 1 and 2, respectively.

As shown in FIG. 3, the robotic system 300 may include a robotic body302, a robotic hip 304 connected to the robotic body 302, and a roboticleg 306 connected to the robotic hip 304. A first robotic foot 308 maybe connected to one end of the robotic leg 306 and a second robotic foot310 may be connected to an opposite end of the robotic leg 306. Therobotic leg 306 may be fully rotatable around an axis of rotation 312defined by the robotic hip 304. Further, the robotic hip 304 may belinearly movable along the robotic leg 306 to one or more positionsbetween the one end of the robotic leg 306 and the opposite end of therobotic leg 306.

Yet further, the robotic system 300 may include a second robotic hip 314connected to the robotic body 302 and a second robotic leg 316 connectedto the second robotic hip 314. A third robotic foot 318 may be connectedto one end of the second robotic leg 316 and a fourth robotic foot 320may be connected to an opposite end of the second robotic leg 316. Thesecond robotic leg 316 may be fully rotatable around a second axis ofrotation 322 defined by the second robotic hip 314, as shown by thecircular arrow around the second axis of rotation 322. In addition, thesecond robotic hip 314 may be linearly movable along the second roboticleg 316 to one or more positions between the one end of the secondrobotic leg 316 and the opposite end of the second robotic leg 316. Forexample, the second robotic hip 314 may be linearly moveable the roboticleg 316 to one or more positions between the third robotic foot 318 andthe fourth robotic foot 320.

Further, the robotic leg 306 and the second robotic leg 308 may bepartially or fully rotatable in the opposite directions of the circulararrows around the axes of rotation 312 and 322, respectively. Therobotic legs 306 and 308 may rotate over varying axes of rotation 312and 322, respectively. For example, the robotic hips 304 and 314 may bemoveable over multiple degrees of freedom (DOF) to vary the axes ofrotation 312 and 322, respectively. In particular, the robotic hips 304and 306 may include ball and socket mechanisms to be movable over themultiple DOF, possibly to change the axes of rotation 312 and 322,respectively.

In some implementations, the robotic system 300 may include differenttypes of robotic feet, possibly for bipedal walking without the windmilltype movements. For example, the second robotic foot 310 may include arubber base that facilitates friction against adjacent surfaces. Forexample, the rubber base may take the form of a rain shoe that createsfriction against the adjacent surfaces covered in rain, snow, and/orother forms of liquids. Further, the first robotic foot 308 may includea wider base than the rubber base. For example, the wider base maydistribute the weight of the robotic system 300 over more area of theadjacent surfaces than the rubber base. In some implementations, thewider base may take the form of a snow shoe that distributes the weightof the robotic system 300 over more area of the adjacent surfacescovered in snow. Further, the third robotic foot 318 may take any of theforms of the robotic foot 308 and the fourth robotic foot 320 may takeany of the forms of the robotic foot 310, among other possibilities.

In some implementations, the robotic system 300 may include differenttypes of robotic legs and/or robotic feet for various types of movementsof the robotic system 300. Further, the robotic system 300 may includedifferent types of feet for walking, jogging, running, and/or jumping.For example, the robotic foot 308 and the third robotic foot 318 may beused for walking, and the second robotic foot 310 and the fourth roboticfoot 320 may be used for running and jumping, among other possibilities.Further, the robotic leg 306 may include a first spring 324 that appliesa first force against the second robotic foot 310. Further, the secondrobotic leg 316 may include a second spring 326 that applies a secondforce against the fourth robotic foot 320. As such, the first spring andthe second spring may store energy for applying the first force and thesecond force, respectively, thereby springing the robotic system 302 offground surfaces.

In some implementations, the robotic system 300 may include anon-transitory computer-readable medium that stores program instructionsexecutable by one or more processors, such as the processor 106 of therobotic system 100 described above in relation to FIG. 1. The programinstructions may cause the robotic system 300 to perform operations. Forexample, the robotic hip 304 may move along the robotic leg 306 to afirst position of the one or more positions between the one end of therobotic leg 306 and the opposite end of the robotic leg 306. Further,the second robotic hip 314 may move along the second robotic leg 316 toa second position of the one or more positions between the one end ofthe second robotic leg 316 and the opposite end of the second roboticleg 316.

In some implementations, a first length of the robotic leg 306 may beapproximately equivalent to a second length of the second robotic leg316. For example, the first position may be approximately half waybetween the one end of the robotic leg 306 proximately connected to thefirst robotic foot 308 and the opposite end of the robotic leg 306proximately connected to the second robotic foot 310. Further, thesecond position may be approximately half way between the one end of thesecond robotic leg 316 proximately connected to the third robotic foot318 and the opposite end of the second robotic leg 316 proximatelyconnected to the fourth robotic foot 320. As such, the robotic system300 may stand such that the robotic hip 304 may be approximately levelwith the second robotic hip 314.

In some implementations, the robotic system 300 may cause the roboticleg 306 to rotate up to 360 degrees around the axis of rotation 312defined by the robotic hip 304 and cause the second robotic leg 316 torotate up to 360 degrees around the second axis of rotation 322 definedby the second robotic hip 314. In particular, the robotic leg 306 andthe second robotic leg 316 may rotate with an approximate phasedifference of 90 degrees. Thus, the robotic leg 306 may rotate firstfollowed by the second robotic leg 316 rotating thereafter.

In some implementations, the robotic system 300 may cause the roboticleg 306 up to rotate up to 180 degrees around the axis of rotation 312defined by the robotic hip 304, where the weight of the robotic system300 is shifted from being placed on the second robotic foot 310 to thefirst robotic foot 308. In particular, the robotic leg 306 may rotate inthe direction of the circular arrow around the axis of rotation 312,thereby switching the weight from being placed on the second roboticfoot 310 to the first robotic foot 308.

Further, the robotic system 300 may cause the second robotic leg 316 torotate up to 180 degrees around the second axis of rotation 322 definedby the second robotic hip 314, where the weight of the robotic system isshifted from being placed on the fourth robotic foot 320 to the thirdrobotic foot 318. In particular, the second robotic leg 316 may rotatein the direction of the circular arrow around the axis of rotation 322,thereby switching the weight from being placed on the fourth roboticfoot 320 to the third robotic foot 318. Based on causing the robotic leg312 and the second robotic leg 322 to rotate, the robotic system 300 maytake an initial step with the first robotic foot 308 and a subsequentstep with the third robotic foot 318.

FIG. 4 is a flow chart 400, according to example implementations. Theseimplementations may be carried out by one or more of the robotic systemsas described above in relation to FIGS. 1-3 or any other robotic systemsdescribed herein.

At block 402, a robotic system may move a robotic hip linearly along arobotic leg to one or more positions between one end of the robotic legand an opposite end of the robotic leg. The robotic leg may include afirst robotic foot connected to the one end of the robotic leg and asecond robotic foot connected to the opposite end of the robotic leg.

For example, block 402 may be carried out by the robotic system 300moving the robotic hip 304 linearly along the robotic leg 306 to one ormore positions between one end of the robotic leg 306 and an oppositeend of the robotic leg 306. Further, the robotic leg 306 may include thefirst robotic foot 308 connected to the one end of the robotic leg 306and the second robotic foot 310 connected to the opposite end of therobotic leg 306.

Further, the robotic system 300 may move the second robotic hip 314linearly along the second robotic leg 316 to one or more positionsbetween one end of the second robotic leg 316 and an opposite end of thesecond robotic leg 316. Further, the second robotic leg 316 may includea third robotic foot 318 connected to the one end of the second roboticleg 316 and a fourth robotic foot 320 connected to the opposite end ofthe second robotic leg 320.

Yet further, a first length of the robotic leg 306 may be approximatelyequivalent to a second length of the second robotic leg 316. Thus,moving the robotic hip 304 linearly along the robotic leg 306 mayinclude moving the robotic hip 304 to a first position approximatelyhalfway between the one end of the robotic leg 306 and the opposite endof the robotic leg 306. Further, moving the second robotic hip 314linearly along the second robotic leg 316 may include moving the secondrobotic hip 314 to a second position approximately halfway between theone end of the second robotic leg 316 and the opposite end of the secondrobotic leg 316.

As noted above, a robotic hip may move linearly along a respectiverobotic leg. Yet further, the robotic leg may cause the robotic hip tomove the along the robotic leg to one or more positions along therobotic leg between one end of the robotic leg and an opposite end ofthe robotic leg. For example, the robotic leg may include one or moremotors connected to the robotic hip that positions the robotic hip to aparticular position of the one or more positions along the robotic legbetween the one end of the robotic leg and an opposite end of therobotic leg.

At block 404, the robotic system may rotate the robotic leg around anaxis of rotation defined by the robotic hip. For example, block 404 maybe carried out by the robotic system 300 rotating the robotic leg 306around the axis of rotation 312 defined by the robotic hip 304. Further,the robotic system 300 may rotate the second robotic leg 316 around thesecond axis of rotation 322 defined by the second robotic hip 314.Further, based on rotating the robotic leg 306 and the second roboticleg 322, the implementations may include causing the robotic system 300to take an initial step with the first robotic foot 308 and a subsequentstep with the third robotic foot 318.

In some implementations, rotating the robotic leg 306 includes rotatingthe robotic leg 306 up to 180 degrees around the axis of rotation 312defined by the robotic hip 304, where rotating the robotic leg 306causes the weight of the robotic system to shift from being placed onthe second robotic foot 310 to the first robotic foot 308. Further,rotating the second robotic leg 316 may include rotating the secondrobotic leg 316 up to 180 degrees around the second axis of rotation 322defined by the second robotic hip 314, where rotating the second roboticleg 316 causes the weight of the robotic system 300 to shift from beingplaced on the fourth robotic foot 320 to the third robotic foot 318.

In some implementations, rotating the robotic leg 306 may includerotating the robotic leg 316 up to 360 degrees around the axis ofrotation 312 defined by the robotic hip 304. Further, the robotic system300 rotating the second robotic leg 316 may include rotating the secondrobotic leg 316 up to 360 degrees around the second axis of rotation 322defined by the second robotic hip 314. As such, the robotic leg 306 andthe second robotic leg 316 may rotate with an approximate phasedifference of approximately 90 degrees.

In practice, the robotic systems may perform the blocks in the flowchart 400 to take one or more steps for bipedal walking, jogging,running, and/or jumping. Further, in some implementations, the roboticsystem 300 may apply, by the first spring 324, a first force against thethird robotic foot 310 and apply, by the second spring 326, a secondforce on the fourth robotic foot 320. Thus, the robotic system 300 maybe spring over objects that may be in its path.

FIGS. 5A and 5B depict aspects of a robotic system 500, according toexample implementation. The implementations of the flow chart 400 mayalso be carried out by the robotic system 500. The robotic system 500may take, for example, the form of a bipedal robot device and/or amulti-legged robot device described above in relation to FIGS. 1 through4. Further, the robotic system 500 may include, for example, one or moreof the parts described above in relation to the FIGS. 1 through 4. Forinstance, the robotic system 500 may take the form of the robotic system300 described above in relation to FIG. 3.

For example, the robotic system 500 may include a robotic body 502, arobotic hip 504, a first robotic foot 508, and a second robotic foot510. Further, the robotic system 500 may include a second robotic hip, athird robotic foot 518, and a fourth robotic foot 520. Yet further, therobotic system 500 may include a first axis of rotation 512 defined bythe robotic hip 504 and a second axis of rotation defined by the secondrobotic hip. As such, the robotic system 500 may perform one or moreoperations that may be performed by the robotic system 300 describedabove in relation to FIG. 3.

FIGS. 5A and 5B may illustrate stages 1 through 6 of the robotic system500. Further, the FIGS. 5A and 5B may illustrate a side-view of therobotic device 500 such that the first axis of rotation 512 may be shownin the stages 1 through 6. For purposes of illustration and explanation,and without any limitations, the first robotic hip 504 and the secondrobotic hip may be approximately level such that they are equivalentdistances away from the from the surface 522. Yet, the first robotic hip512 and the second robotic hip are linearly movable along respectiverobotic legs to be different distances away from the surface 522.

As shown in stage 1 of FIG. 5A, the robotic system 500 may be in astanding position, possibly before taking one or more steps. The roboticsystem 500 may have moved the robotic hip 504 linearly along the roboticleg 506 to one end of the robotic leg 506 proximately connected to thefirst robotic foot 508. Further, the robotic system 500 may have movedthe second robotic hip linearly along the second robotic leg 516 to oneend of the second robotic leg 516 proximately connected to the thirdrobotic foot 518.

As shown in stage 2, the robotic system 500 may switch robotic feet,possibly to shift the weight of the robotic system 500 from one roboticfoot to another robotic foot. For example, the robotic system 500 maymove the second robotic hip linearly along the second robotic leg 516.Further, the second robotic hip may move to a position between the oneend of the second robotic leg 516 and an opposite end of the secondrobotic leg 516 proximately connected to the fourth robotic foot 520.

Further, as shown in stage 2, the robotic system 500 may lift the secondrobotic leg 516 off the surface 522 and balance the weight of therobotic system 500 on the second robotic foot 510 while rotating thesecond robotic leg 516. The robotic system 500 may rotate the secondrobotic leg 516 approximately 90 to 180 degrees around the second axisof rotation defined by the second robotic hip. For instance, the roboticsystem 500 may switch from the fourth robotic foot 520 to the thirdrobotic foot 518. In this way, the weight of the robotic system 500 maybe shifted from being placed on the fourth robotic foot 520 to the thirdrobotic foot 518.

As shown in stage 3, the robotic system 500 may take a step forward. Forexample, the robotic system 500 may move the second robotic hip linearlyalong the second robotic leg 516 to the opposite end of the secondrobotic leg 516. Further, as shown in stage 3, the robotic system 500may rotate the second robotic leg 516 approximately 45 degrees aroundthe second axis of rotation to take a step forward with the thirdrobotic foot 518.

As shown in stage 4, the robotic system 500 may move in the windmilltype fashion. For example, the robotic system 500 may move the robotichip 504 linearly along the robotic leg 506 to a first positionapproximately halfway between the one end of the robotic leg 506 and anopposite end of the robotic leg 506 proximately connected to the secondrobotic foot 510. Further, the robotic system 500 may move the secondrobotic hip 514 linearly along the second robotic leg 516 to a secondposition approximately halfway between the one end of the second roboticleg 516 and the opposite end of the second robotic leg 516.

Further, as shown in stage 4, the robotic leg 506 and the second roboticleg 516 may rotate around the first axis of rotation 512 and the secondaxis of rotation, respectively. In addition, the robotic leg 506 and thesecond robotic leg 516 may rotate with a phase difference ofapproximately 90 degrees. In particular, the first robotic foot 508 maytake a first step, followed by the third robotic foot 518 taking asecond step, followed by the second robotic foot 510 taking a thirdstep, and followed by the fourth robotic foot 520 making a fourth step.As such, the robotic leg 506 and the second robotic leg 516 may move inthe windmill type fashion to propel the robotic system 500 in a givendirection.

As shown in stage 5 of FIG. 5B, the robotic system 500 may move from thesurface 522 to an elevated surface 524. For example, the robotic system500 may move the robotic hip 504 linearly along the robotic leg 506 tothe one end of the robotic leg 506. The second robotic hip 514 may be inthe second position approximately halfway between the one end of thesecond robotic leg 516 and the opposite end of the second robotic leg516

Further, as shown in stage 5, the robotic system 500 may rotate thesecond robotic leg 516 around the second axis of rotation such that thethird robotic foot 518 may take a step on the elevated surface 524. Forexample, the robotic system 500 may build speed towards the elevatedsurface 524, and the second robotic leg 516 and the third robotic foot518 may be used to lift, vault, and/or catapult the robotic system 500above the elevated surface 524. Further, as show in stage 6, the roboticsystem 500 may continue moving on the elevated surface 524.

As such, the robotic system 500 may take one or more steps for bipedalwalking, jogging, running, and/or jumping. In particular, the roboticsystem 500 may walk without the making windmill type movements. Yet, therobotic system 500 may make the windmill type movements to conservepower, reduce the motion of robotic legs swinging forward to take steps,and decrease the chances of tripping over objects. Further, the roboticsystem 500 may include the first spring 324 and the second spring 326 tospring over objects as described above in relation to FIGS. 3 and 4.

III. ADDITIONAL IMPLEMENTATIONS

FIGS. 6A and 6B depict aspects of a robotic system, according to anexample implementation. The robotic system 600 may take the form of abipedal robot device as described above in relation to FIGS. 1-5.Further, the robotic system 600 may include, for example, one or more ofthe parts of the robotic systems described above in relation FIGS. 1-5,respectively.

For example, as shown in FIG. 6A, the robotic system 600 may include arobotic body 602, a robotic hip 604 connected to the robotic body 602, aball screw 628 connected to the robotic hip 604, and robotic leg 606connected to the robotic hip 604 parallel to the ball screw 628.Further, the robotic system 600 may include a second robotic hip 614connected to the robotic body 602, a second ball screw 630 connected tothe second robotic hip 614, and a second robotic leg 616 connected tothe second robotic hip 614 parallel to the second ball screw 630.

Further, the robotic leg 606 may include a first spring 624 that appliesa first force against a second robotic foot 610. Yet further, the secondrobotic leg 616 may include a second spring 626 that applies a secondforce against a fourth robotic foot 620. As such, the first spring andthe second spring may store energy for applying the first force and thesecond force, respectively.

FIG. 6B may depict aspects of a robotic leg and robotic hip. Forexample, the robotic leg 606 may include a ball screw 628, possibly suchthat the ball screw 628 is parallel to the robotic leg 606 and/or insidethe robotic leg 606. Further, the robotic hip 604 may include a motor632 that is linearly movable to one or more positions along the ballscrew 628 between one end of the robotic leg 606 and an opposite end ofthe robotic leg 606.

As noted, FIG. 6B may depict aspects of the ball screw 628 parallel torobotic leg 606. The second robotic leg 616 may also include the ballscrew 630, possibly such that the second ball screw 630 is parallel tothe robotic leg 616 and/or inside the robotic leg 616. Further, thesecond robotic hip 614 may include a second motor 634 that is linearlymovable to one or more positions along the second ball screw 630 betweenone end of the second robotic leg 616 and an opposite end of the secondrobotic leg 616. As such, the second robotic leg 616 may have one ormore parts of the robotic leg 606.

In some implementations, the ball screws 628 and 630 may be mechanicalactuators that translate rotation motion to linear motion of the robotichips 604 and 614 to one or more positions along the robotic legs 606 and616, respectively. Further, the robotic hips 604 and 614 may movelinearly up and down the ball screws 628 and 630, respectively, with lowinternal friction and high precision. In some instances, the ball screws628 and 630 may each withstand impacts and heavy loads, possiblyincreasing the durability of the robotic system 600.

Further, the mass of the ball screws 628 and 630 may each beapproximately 0.1-5 kg, the mass of the robotic legs 606 and 616 mayeach be approximately 1-10 kg, and the mass of the motors 632 and 634may each be approximately 10-20 kg. As such, the ball screws 628 and 630may each have a smaller mass than the robotic legs 606 and 616,respectively. Further, the ball screws 628 and 630 may each have asmaller mass than the motors 632 and 634, thereby reducing inertialeffects when the robotic legs 606 and 616 rotate around the robotic hip604 and the second robotic hip 614, respectively. By reducing suchinertial effects, the dynamics of the robotic system 600 (e.g., therobotic legs 606 and 616) may be controlled.

In some implementations, the robotic leg 606 may be fully rotatablearound an axis of rotation 612 defined by the robotic hip 604. Further,a first robotic foot 608 may be connected to the one end of the roboticleg 606 and a second robotic foot 610 may be connected to the oppositeend of the robotic leg 606. Further, the second robotic leg 616 may befully rotatable around a second axis of rotation 622 defined by thesecond robotic hip 614. Further, a third robotic foot 618 may beconnected to the one end of the robotic leg 616 and a fourth roboticfoot 620 may be connected to the opposite end of the second robotic leg616.

Further, as shown in FIG. 6B, the robotic leg 606 may include a torquelimiter 636 that determines an amount of torque applied by the motor632, an encoder 638 that determines a particular position of the motor632 from the one or more positions along the ball screw 628, and anelectromagnetic brake 640 that holds the motor 632 at the particularposition and releases the motor 632 from the particular position.Further, the motor 632 and the electromagnetic brake 640 may also bepositioned in other areas of the robotic leg 606. For example, in someimplementations, the motor 632 may be proximate to the torque limiter636. Further, the motor 632 may be in a fixed or semi-fixed positionproximate to the torque limiter 636. As such, the motor 632 may turn theball screw 628 to move the robotic hip 604 to one or more positionsalong the ball screw 628.

In some implementations, the robotic system 600 may include acomputer-readable medium that stores program instructions executable byone or more processors such as the processor 106 of the robotic system100 described above in relation to FIG. 1. The program instructions maybe executed by the processors to cause the robotic system 600 to performoperations. For example, the processors may cause the torque limiter 636to determine that the amount of torque applied by the motor 632 exceedsone or more torque thresholds. Based on determining the amount of torqueapplied, the processors may cause the electromagnetic brake 640 to applya friction to hold the motor 632 at the particular position of along theball screw 628.

In some implementations, the electromagnetic brake 640 may include brakepads that block the motor 632 from moving on the ball screw 628. Yetfurther, the electromagnetic brake 640 may apply the pressure on themotor 632 to hold the motor 632 in place on the ball screw 628. By theelectromagnetic brake 640 blocking the motor 632 and/or applyingpressure on the motor 632, the motor 632 may reduce the amount of torqueapplied below the one or more torque thresholds.

In some implementations, the robotic system 600 may include atemperature sensor 642 that measures the temperature of the roboticsystem 600 based on the friction applied to hold the motor 640 at theparticular position along the ball screw 628. For example, thetemperature sensor 642 may measure the temperature of the motor 632, theelectromagnetic brake 640, and/or the ball screw 628, among other partsof the robotic system 600.

Further, the robotic system 600 may determine that the measuredtemperature exceeds one or more temperature thresholds. Based onexceeding the one or more temperature thresholds, the electromagneticbrake 640 may release the friction applied to hold the motor 632 at theparticular position along the ball screw 628. As such, the motor 632 mayincrease the amount of torque applied by the motor 632. Thus, afterreleasing the friction applied, the temperature of the robotic system600 may decrease below the one or more temperature thresholds.

In some implementations, the motor 632 and the electromagnetic brake 640may tradeoff applying torque and friction, respectively, to hold themotor 632 at the particular position. For example, the motor 632 mayapply torque to hold the motor 632 in place until the one or more torquethresholds are exceeded, thereby causing the electromagnetic brake 640to apply the friction to hold the motor 632 in place. The friction maycause the motor 632 to lower the amount of torque applied to hold themotor 632 in place.

Further, the electromagnetic brake may hold the motor 632 in place untilthe one or more temperature thresholds are exceeded, thereby causing themotor 632 to apply more torque to hold the motor 632 in place. As such,the electromagnetic brake 640 may release the friction applied to holdthe motor 632 in place. In practice, the one or more torque thresholdsand the one or more temperature thresholds may be predetermined and/ormodified.

FIG. 7 is a flow chart 700, according to example implementations. Theimplementations may be carried out by one or more of the robotic systemsdescribed above in relation to FIGS. 1 through 6B.

At block 702, the robotic system may move a motor of a robotic hiplinearly along a ball screw connected parallel to a robotic leg, wherethe motor moves to one or more positions along the ball screw betweenone end of the robotic leg and an opposite end of the robotic leg, wherethe robotic hip is connected to a robotic body. For example, the roboticsystem may move the robotic hip linearly along the robotic leg in anymanner described above in relation to block 402 of FIG. 4.

Further, block 702 may be carried out by the robotic system 600 movingthe motor 632 of the robotic hip 604 linearly along the ball screw 628connected parallel to the robotic leg 606, where the motor 632 moves toone or more positions along the ball screw 628 between one end of therobotic leg 606 and an opposite end of the robotic leg 606.

In some implementations, the robotic system 600 may move a second motor634 of a second robotic hip 614 linearly along a second ball screw 630connected parallel to a second robotic leg 616, where the second motor634 moves to one or more positions along the ball screw 630 between oneend of the second robotic leg 616 and an opposite end of the secondrobotic leg 616. As shown, the second robotic hip 614 may be connectedto the robotic body 602.

In some implementations, the torque limiter 636 may determine that anamount of torque applied by the motor 632 exceeds one or more torquethresholds. Further, the encoder 638 may determine a particular positionof the motor 632 from the one or more positions along the ball screw628. Based on determining the particular position of the motor 632, theelectromagnetic brake 640 may apply a friction to hold the motor 632 atthe particular position along the ball screw 628. Yet further, the motor632 may reduce the torque applied by the motor 632 below the one or moretorque thresholds.

In some implementations, the temperature sensor 642 may determine atemperature of the robotic system 600 based on the friction applied tohold the motor 632 at the particular position along the ball screw 628.Based on determining the temperature of the robotic system 600, theelectromagnetic brake 640 may release the friction applied to hold themotor 632 at the particular position along the ball screw 638. Yetfurther, the motor may increase the amount of torque applied to hold themotor 632 at the particular position along the ball screw 628.

At block 704, the robotic system may rotate the robotic leg around anaxis of rotation defined by the robotic hip. For example, the roboticsystem may rotate the robotic leg around the axis of rotation defined bythe robotic hip in any manner described above in relation to block 404of FIG. 4.

Further, block 704 may be carried out by the robotic system 600 rotatingthe robotic leg 606 around the axis of rotation 612 defined by therobotic hip 604. Yet further, the robotic system 600 may rotate thesecond robotic leg 616 around a second axis of rotation 622 defined bythe second robotic hip 634.

In some implementations, the robotic leg 606 may rotate around the axisof rotation 612 defined by the robotic hip 612 includes the robotic leg606 rotating up to 180 degrees around the axis of rotation 612, where afirst robotic foot 608 is connected to the one end of the robotic leg606 and a second robotic foot 610 is connected to the opposite end ofthe robotic leg 606.

In some implementations, the robotic leg 606 may rotate up to 180degrees around the axis of rotation 612 defined by the robotic hip 604,where rotating the robotic leg 606 causes the weight of the roboticsystem to shift from being placed on the second robotic foot 610 to thefirst robotic foot 608. Further, rotating the second robotic leg 616 mayinclude rotating the second robotic leg 616 up to 180 degrees around thesecond axis of rotation 622 defined by the second robotic hip 614, whererotating the second robotic leg 616 causes the weight of the roboticsystem 600 to shift from being placed on the fourth robotic foot 620 tothe third robotic foot 618.

At block 706, based on rotating the robotic leg, the robotic system maycause the robotic leg to take a step. Further, based on rotating thesecond robotic leg, the robotic system may cause the second robotic legto take a step. In some implementations, the robotic system may causethe robotic leg and/or the second robotic leg to take a step in anymanner described above in relation to FIGS. 1 through 6.

IV. ADDITIONAL EXAMPLES OF ROBOTIC SYSTEMS

FIG. 8 depicts a robotic system, according to an example implementation.The robotic system 800 may include, for example, one or more parts ofthe robotic systems described above in relation to FIGS. 1-7. Forexample, the robotic legs 814 and 816 may include sensors 110 such as asensor that measures inertial forces and/or G-forces in multipledimensions, a force-torque sensor, a ground force sensor, a frictionsensor, and/or a ZMP sensor, among other possibilities. Further, therobotic system 800 may include one or more motors that generate heat andare cooled by lower temperature liquids around the motors. As such, therobotic system 800 may also engage in bipedal walking.

The robotic system 800 may include a robotic head 802, a robotic body804, two robotic arms 806 and 808, two robotic hips 810 and 812, and tworobotic legs 814 and 816. Further, the robotic legs 814 and 816 mayinclude two robotic knees 818 and 820, two robotic ankles 822 and 824,and two robotic feet 826 and 828, respectively. As such, the roboticsystem 800 may be capable of using robotic arms 806 and 808 to interactwith an environment, possibly beyond the capabilities of the roboticsystem 300.

FIG. 9 depicts aspects of a robotic system, according to an exampleimplementation. The robotic system 900 may include, for example, one ormore parts of the robotic systems described above in relation to FIGS.1-8. As shown, FIG. 9 may illustrate a side view of the robotic system900. The robotic system 900 may include a robotic head 902, a roboticbody 904, a robotic arm 906, a robotic hip 910, a second robotic hip912, a robotic leg 914, and a second robotic leg 916. Further, therobotic legs 914 and 916 may include a robotic knee 918 and a secondrobotic knee 920, respectively. Further, the robotic legs 914 and 916may include a robotic ankle 922 and a second robotic ankle 924, and arobotic foot 926 and a second robotic foot 928, respectively.

In some implementations, the robotic systems described above in relationto FIGS. 1-9 may be used in environments involving natural andhuman-made disasters. For example, these robotic systems may performactivities in disaster zones to help victims in the vicinity of suchdisaster zone. In particular, these robotic systems may adapt to varioustypes of sites that the robotic systems may not have previouslyencountered. As such, these robotic systems may demonstrate someautonomy in making decisions and data obtained from sensors 110.Further, these robotic systems may be controlled remotely based onreceiving one or more commands to perform operations.

For example, the robotic systems may travel through areas that may beunsafe for living beings. In particular, these robotic systems mayoperate in natural disaster areas affected by earthquakes, fires,natural gas leaks, and/or exposures to radioactive elements, among otherpossible areas. For example, the robotic system 800 of FIG. 8 may open adoor using the robotic arms 806 and 808. Further, the robotic arms 806and/or 808 may keep the door open while the robotic legs 814 and 816walk through the doorway. The robotic system 800 may pick up debris thatobstructs pathways, possibly using the robotic arms 806 and 808 to movethe debris. The robotic system 800 may cut through walls using one orboth of the robotic arms 806 and/or 808. For example, the robotic arm806 may include a saw that may protrude from the robotic arm 806 suchthat the robotic arm 806 may be directed to cut an opening into a wall.As such, the robotic system 800 may create escape routes for savingliving beings that may be trapped in confined areas.

The robotic systems may operate a diverse assortment of tools, possiblydesigned to be used by human persons. For example the robotic system 900may identify a hose that may be connected to water valve. The roboticsystem 900 may carry the hose and connect the hose to the water valveusing the robotic arm 906. Further, the robotic system 900 may use therobotic arm 906 to turn a wheel of the valve that allows water to flowthrough the valve and into the hose. As such, the robotic system 900 maycontrol the valve and carry the hose to various locations, providingwater to such locations.

In some implementations, the robotic systems may be used in variousmanufacturing facilities. For example, the robotic systems may be usedin an assembly line with multiple work stations along the assembly linethat add parts to a partially-finished machine. The robotic systems maymove parts to various work stations on the assembly line and also fromone work station to another. Further, the robotic systems may placeparts on the partially-finished machine to facilitate the creation of afinished machine, among other possibilities.

FIG. 10 depicts aspects of a liquid-cooled device 1000, according to anexample implementation. The liquid-cooled device 1000 may beincorporated, for example, with the robotic systems as described abovein relation to FIGS. 1-9. For example, the liquid-cooled device 1000 maybe incorporated with any of the motors described above that generateheat. In particular, one or more liquid-cooled devices 1000 may beincorporated in the hips 304 and 314 of the robotic system 300. Inparticular, the one or more liquid-cooled devices 1000 may includemotors to move the robotic hips 304 and 314 along robotic legs 306 and316, respectively.

For example, one or more liquid-cooled devices 1000 may be used to movethe robotic hip 304 along the robotic leg 306 to a first position of theone or more positions between the one end of the robotic leg 306 and theopposite end of the robotic leg 306. Further, the one or moreliquid-cooled devices 1000 may be used to move the second robotic hip314 along the second robotic leg 316 to a second position of the one ormore positions between the one end of the second robotic leg 316 and theopposite end of the second robotic leg 316, as described above inrelation to FIG. 3. Yet further, the one or more liquid-cooled devices1000 may include the motors 632 and 634 to move the motors 632 and 634along the ball screws 628 and 630, respectively, as described above inrelation to FIG. 6.

As shown, FIG. 10 may illustrate a side view of the liquid-cooled device1000. The liquid-cooled device 1000 may be a water-cooled device thatactively controls the temperature of the motor 1002. For example, theliquid-cooled device 1000 may estimate the internal temperature of themotor 1002 and based on such estimations, the liquid-cooled device 1000may cool the motor 1002 by passing cooling liquids around the motor1002. As such, robotic systems with the liquid-cooled device 1000 may beable to create high torque forces using the motor 1002 to move roboticlimbs, but also prevent overheating the motor 1002.

The motor 1002 may be a 50-350 Watt brushless motor operable at highspeeds. Channels 1004, 1006, and 1008 may make contact with the motor1002 to absorb, transfer, and/or displace heat (e.g., thermal energy)from the motor 1002, possibly to reduce the temperature of the motor1002. Further, the channels 1004-1008 may encapsulate the motor 1000,possibly to increase contact with the surface area of the motor 1002.Thus, the channels 1004-1008 may absorb heat produced by the motor 1002and the surface contact of the channels 1004-1008 with the motor 1002may cool the motor 1002.

Valves 1014 and 1016 may control liquids flowing in and out of channels1004 and 1006, respectively. For example, a liquid 1010 may flow intothe channel 1004 to cool the motor 1002 and a liquid 1012 may flow outof channel 1006. The liquid 1010 may have a lower temperature than themotor 1002 and the liquid 1012 may have a higher temperature than theliquid 1010. Thus, the channels 1004 and 1006 may be connected bychannel 1008 such that the liquid 1010 may flow into channel 1004through channel 1008 and liquid 1012 may flow out of the channel 1006.In some implementations, there may be a constant flow of liquid 1010flowing into the channel 1004 and liquid 1012 flowing out of the channel1006. Further, the liquid 1012 may flow into a reservoir to cool theliquid 1012 such that the liquid 1012 may flow back into channel 1004 tocool the motor 1002. The liquids 1010 and 1012 may also flow in anopposite direction such that liquid 1012 may flow into channel 1006through channel 1008 and liquid 1010 may flow out of channel 1004.

The temperature of a motor may be difficult to determine. As such, thechannel 1006 may include a sensor 1012. The sensor 1012 may include, forexample, one or more of the sensors 110 described above in relation toFIG. 1. Thus, the sensor 1012 may determine the temperature of theliquid 1010 to estimate the temperature of the motor 1002. For example,the sensor 1012 may determine that the temperature of the liquid 1012meets or exceeds a temperature threshold, possibly approximating 100 to150 degrees Celsius. As such, the valve 1016 may open to release theliquid 1010.

The robotic system may include a driver operable to deliver high currentto the motor 1002. By using high power sources to power the driver, thedriver may deliver approximately 40-240 Amperes to the motor 1000.Further, the driver may include a copper layer that may also be cooledby channels 1004-1008 of the liquid-cooled device 1000 and the liquids1008 and 1010. As such, with measures for preventing overheating, themaximum current of the motor 1002 may be approximately 20 times greaterthan conventional motors. Thus, the drivers enable the motor 1002 toproduce larger torque forces in a shortened period of time.

V. CONCLUSION

While various aspects and implementations have been disclosed herein,other aspects and implementations will be apparent to those skilled inthe art. The various aspects and implementations disclosed herein arefor purposes of illustration and are not intended to be limiting, withthe true scope being indicated by the following claims.

We claim:
 1. A robotic system comprising: a robotic body; a robotic hipconnected to the robotic body; a ball screw connected to the robotichip; and a robotic leg connected to the robotic hip parallel to the ballscrew, wherein the robotic hip comprises a motor that is linearlymovable to one or more positions along the ball screw between one end ofthe robotic leg and an opposite end of the robotic leg, wherein therobotic leg is fully rotatable around an axis of rotation defined by therobotic hip, and wherein a first robotic foot is connected to the oneend of the robotic leg and a second robotic foot is connected to theopposite end of the robotic leg.
 2. The robotic system of claim 1,wherein a mass of the ball screw is approximately 0.1-5 kg, wherein amass of the robotic leg is approximately 1-10 kg, and wherein a mass ofthe motor is approximately 10-20 kg.
 3. The robotic system of claim 1,wherein the robotic leg further comprises a torque limiter thatdetermines an amount of torque applied by the motor, an encoder thatdetermines a particular position of the motor from the one or morepositions along the ball screw, and an electromagnetic brake that holdsthe motor at the particular position and releases the motor from theparticular position.
 4. The robotic system of claim 3, wherein therobotic system further comprises a computer-readable medium havingstored thereon program instructions that, when executed by one or moreprocessors of the robotic system, cause the robotic system to performoperations comprising: determining, by the torque limiter, that theamount of torque applied by the motor exceeds one or more torquethresholds; based on determining the amount of torque applied, causingthe electromagnetic brake to apply a friction to hold the motor at theparticular position of along the ball screw; and causing the motor toreduce the amount of torque applied by the motor below the one or moretorque thresholds.
 5. The robotic system of claim 4, wherein the roboticsystem further comprises a temperature sensor that measures temperatureof the robotic system based on the friction applied to hold the motor atthe particular position along the ball screw.
 6. The robotic system ofclaim 5, wherein the operations further comprise: determining that themeasured temperature exceeds one or more temperature thresholds; basedon exceeding the one or more temperature thresholds, causing theelectromagnetic brake to release the friction applied to hold the motorat the particular position along the ball screw; and causing the motorto increase the amount of torque applied by the motor.
 7. The roboticsystem of claim 1, further comprising: a second robotic hip connected tothe robotic body; a second ball screw connected to the second robotichip; and a second robotic leg connected to the second robotic hipparallel to the second ball screw, wherein the second robotic hipcomprises a second motor that is linearly movable to one or morepositions along the second ball screw between one end of the secondrobotic leg and an opposite end of the second robotic leg.
 8. Therobotic system of claim 1, further comprising a liquid-cooled deviceconfigured to cool the motor.
 9. A method comprising: moving, by arobotic system, a motor of a robotic hip linearly along a ball screwconnected parallel to a robotic leg, wherein the motor moves to one ormore positions along the ball screw between one end of the robotic legand an opposite end of the robotic leg, wherein the robotic hip isconnected to a robotic body; rotating, by the robotic system, therobotic leg around an axis of rotation defined by the robotic hip,wherein the robotic leg is fully rotatable around the axis of rotationdefined by the robotic hip, and wherein a first robotic foot isconnected to the one end of the robotic leg and a second robotic foot isconnected to the opposite end of the robotic leg; based on rotating therobotic leg, causing, by the robotic system, the robotic leg to take astep with the first robotic foot.
 10. The method of claim 9, wherein amass of the ball screw is approximately 0.1-5 kg, wherein a mass of therobotic leg is approximately 1-10 kg, and wherein a mass of a ball screwmotor is approximately 10-20 kg.
 11. The method of claim 9, wherein therobotic leg further comprises a torque limiter, an encoder, and anelectromagnetic brake, the method further comprising: determining, bythe torque limiter, that an amount of torque applied by the motorexceeds one or more torque thresholds; determining, by the encoder, aparticular position of the motor from the one or more positions alongthe ball screw; based on determining the particular position of themotor, causing the electromagnetic brake to apply a friction to hold themotor at the particular position along the ball screw; and causing themotor to reduce the torque applied by the motor below the one or moretorque thresholds.
 12. The method of claim 11, wherein the roboticsystem further comprises a temperature sensor, the method furthercomprising: determining, by the temperature sensor, a temperature of therobotic system based on the friction applied to hold the motor at theparticular position along the ball screw; based on determining thetemperature of the robotic system, causing the electromagnetic brake torelease the friction applied to hold the motor at the particularposition along the ball screw; and causing the motor to increase theamount of torque applied by the motor.
 13. The method of claim 9,further comprising: moving, by the robotic system, a second motor of asecond robotic hip linearly along a second ball screw connected parallelto a second robotic leg, wherein the second motor moves to one or morepositions along the ball screw between one end of the second robotic legand an opposite end of the second robotic leg, wherein the secondrobotic hip is connected to the robotic body; rotating, by the roboticsystem, the second robotic leg around a second axis of rotation definedby the second robotic hip; and based on rotating the second robotic leg,causing, by the robotic device, the second robotic leg to take a step.14. A bipedal robot device comprising: a robotic body; a robotic hipconnected to the robotic body; a ball screw connected to the robotichip; and a robotic leg connected to the robotic hip parallel to the ballscrew, wherein the robotic hip comprises a motor that is linearlymovable to one or more positions along the ball screw between one end ofthe robotic leg and an opposite end of the robotic leg, wherein therobotic leg is fully rotatable around an axis of rotation defined by therobotic hip, and wherein a first robotic foot is connected to the oneend of the robotic leg and a second robotic foot is connected to theopposite end of the robotic leg.
 15. The bipedal robot device of claim14, wherein a mass of the ball screw is approximately 0.1-5 kg, whereina mass of the robotic leg is approximately 1-10 kg, and wherein a massof the motor is approximately 10-20 kg.
 16. The bipedal robot device ofclaim 14, wherein the robotic leg further comprises a torque limiterthat determines an amount of torque applied by the motor, an encoderthat determines a particular position of the motor from the one or morepositions along the ball screw, and an electromagnetic brake that holdsthe motor at the particular position and releases the motor from theparticular position.
 17. The bipedal robot device of claim 16, whereinthe bipedal robot device further comprises a computer-readable mediumhaving stored thereon program instructions that, when executed by one ormore processors of the bipedal robot device, cause the bipedal robotdevice to perform operations comprising: determining, by the torquelimiter, that the amount of torque applied by the motor exceeds one ormore torque thresholds; based on determining the amount of torqueapplied, causing the electromagnetic brake to apply a friction to holdthe motor at the particular position of along the ball screw; andcausing the motor to reduce the amount of torque applied below the oneor more torque thresholds.
 18. The bipedal robot device of claim 17,wherein the bipedal robot device further comprises a temperature sensorthat measures temperature of the bipedal robot device based on thefriction applied to hold the motor at the particular position along theball screw.
 19. The bipedal robot device of claim 18, wherein theoperations further comprise: determining that the measured temperatureexceeds one or more temperature thresholds; based on exceeding the oneor more temperature thresholds, causing the electromagnetic brake torelease the friction applied to hold the motor at the particularposition along the ball screw; and causing the motor to increase theamount of torque applied by the motor.
 20. The bipedal robot device ofclaim 14, further comprising a liquid-cooled device configured to coolthe motor.